The present invention relates to a laminate in which silica-based films having different compositions and an organic film are layered, a method of forming the same, an insulating film, and a semiconductor device.
A silica (SiO2)-based film formed by a vacuum process such as a CVD process or an organic film containing an organic polymer as the major component has been used as an interlayer dielectric of a semiconductor device.
In recent years, a spin on glass (SOG) film, which is a coating type insulating film containing a tetraalkoxysilane hydrolysate as the major component, has been used in order to form a more uniform interlayer dielectric. Along with an increase in the degree of integration of a semiconductor device, a low-relative-dielectric-constant interlayer dielectric called an organic SOG containing an organopolysiloxane as the major component has been developed.
However, since an increase in the degree of integration of a semiconductor device has further progressed, further excellent electrical insulation between conductors has been demanded. Therefore, an interlayer dielectric material having a lower relative dielectric constant has been in demand.
As an example of such an interlayer dielectric material, a coating type composition for forming an insulating film having a low relative dielectric constant disclosed in JP-A-2001-256621 can be given. The film-forming composition disclosed in JP-A-2001-256621 is obtained by hydrolysis and condensation of an alkoxysilane in the presence of a metal catalyst. A film having a low relative dielectric constant and a high modulus of elasticity and exhibiting excellent CMP resistance can be obtained by using the film-forming composition.
In a recent semiconductor device manufacturing process, a chemical mechanical polishing (CMP) step has been widely used to planarize a multilayer film. In order to simplify the manufacturing process and to reduce processing damage to the insulating film, a method of forming an organic film on a silica-based film has been proposed. However, when the multilayer film of the silica-based film and the organic film is subjected to processing such as CMP, separation may occur between the silica-based film and the organic film due to poor adhesion between the silica-based film and the organic film.